“自交不亲和性”是很多植物物种中的一个重要机制，用于通过确保拒绝自体花粉来防止近亲繁殖。它是由一个多等位基因的S-位点控制的，后者由花粉（雄性）和雌蕊（雌性）的S-决定因子构成。
Wheeler等人克隆了一个具有高度多态性的、在花粉中表达的基因的三个等位基因；该基因名叫PrpS，来自普通罂粟，它在现有数据库中没有同源基因。PrpS是一种跨膜蛋白，其功能似乎是起花粉S-位点决定因子的作用。这一结果增加了我们对细胞-细胞识别体系的演化的认识。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 459, 992-995 (18 June 2009) | doi:10.1038/nature08027
Identification of the pollen self-incompatibility determinant in Papaver rhoeas
Michael J. Wheeler1,2,3, Barend H. J. de Graaf1,2,3, Natalie Hadjiosif1,2, Ruth M. Perry1, Natalie S. Poulter1, Kim Osman1, Sabina Vatovec1, Andrea Harper1, F. Christopher H. Franklin1 & Vernonica E. Franklin-Tong1
1 School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
2 These authors contributed equally to this work.
Higher plants produce seed through pollination, using specific interactions between pollen and pistil. Self-incompatibility is an important mechanism used in many species to prevent inbreeding; it is controlled by a multi-allelic S locus1, 2. 'Self' (incompatible) pollen is discriminated from 'non-self' (compatible) pollen by interaction of pollen and pistil S locus components, and is subsequently inhibited. In Papaver rhoeas, the pistil S locus product is a small protein that interacts with incompatible pollen, triggering a Ca2+-dependent signalling network, resulting in pollen inhibition and programmed cell death3, 4, 5, 6, 7. Here we have cloned three alleles of a highly polymorphic pollen-expressed gene, PrpS (Papaver rhoeas pollen S), from Papaver and provide evidence that this encodes the pollen S locus determinant. PrpS is a single-copy gene linked to the pistil S gene (currently called S, but referred to hereafter as PrsS for Papaver rhoeas stigma S determinant). Sequence analysis indicates that PrsS and PrpS are equally ancient and probably co-evolved. PrpS encodes a novel 20-kDa protein. Consistent with predictions that it is a transmembrane protein, PrpS is associated with the plasma membrane. We show that a predicted extracellular loop segment of PrpS interacts with PrsS and, using PrpS antisense oligonucleotides, we demonstrate that PrpS is involved in S-specific inhibition of incompatible pollen. Identification of PrpS represents a major advance in our understanding of the Papaver self-incompatibility system. As a novel cell–cell recognition determinant it contributes to the available information concerning the origins and evolution of cell–cell recognition systems involved in discrimination between self and non-self, which also include histocompatibility systems in primitive chordates and vertebrates.
